Unformatted text preview: Student: Grady Simonton Course: Mathll9: Elementary Statistics  Spring 2010  CRN: 49239
Instructor: Shawn Parvini  16 weeks Date: 2/18/10 Book: Triola: Elementary Statistics, lle
Time: 1:58 PM Below are 36 sorted ages of an acting award winner. Find P75 using the method presented in the textbook. 16 22 25 25 28 28 28 29 32 32
33 34 36 37 38 42 48 49 49 50
50 53 53 54 54 58 68 69 72 72
72 75 77 78 79 80 The ﬁrst step in converting from a percentile to the corresponding data value is to arrange the data in order of lowest to
highest. The given data is already sorted, so we can proceed to the next step. k
Next compute L = [E]  n where n is the total number of values in the data set and k is the percentile being used. L is a locator that gives the position of a value. (For example, for the 12th value in the sorted list, L = 12.)
To compute L, ﬁrst determine the values of n and k. n = total number of values in the data set = 36 k is the percentile being used = 75 FindL.
k
L = — n
[ml
_ i 36—27
100 Now the process differs depending on whether or not L is a whole number. Since L = 27 is a whole number, the value of
the kth percentile is midway between the Lth value and the next value in the sorted list.
The Lth = 27th value in the sorted list is 68 and the next value is 69. Finally, ﬁnd Pk = P75 by adding the Lth value, 68, and the next value, 69, and dividing the total by 2. Page 1 ...
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